Greetings All, I have read many upon many articles here regarding GUID
data types and uniqueness. There have been many opinions regarding
the effectiveness of GUID's and when they should/should not be used.
However, every article strongly implies, if it does not state it
outright, that GUID's are always unique. My question is this, what
happens if you have a database that uses GUID's and the NIC is changed
out on the box? From what I understand the MAC address of the NIC is
used as part of the algorithm to generate a GUID. If you change out
the NIC after generating 1 billion GUID's do you run the chance of
generating a duplicate GUID?
I look forward to your insightfulness on this issue.
Let's say that I have a database with 2 tables named 'TableA' and 'TableB'. Each one of those two tables contains the two fields 'MyKey' and 'MyData'. The field 'MyKey' has the type 'uniqueidentifier' and its default value is 'getnewid()'.
Now I would like to consider a third table named 'TableC' with two fields 'KeyRef' and 'MetaData'. The type of 'KeyRef' is 'uniqueidenfier' and corresponds to an element of either 'TableA' or 'TableB'.
If the GUID identifiers are trully unique then there is no issue to proceed that way (I am not consering perf matters here). On the contrary, if GUID are not unique, then there is a collision possibility.
My question is simply: can I consider the GUID to be unique in MS SQL Server (2000 or 2005).
In Access, newID returns a unique for the table. In SQL Server, newid()returns a GUID - unique in the world. I do not need or desire thatcomplexity. Is there a way to get a simple unique int on the table inSQL Server?Brad Eckhttp://www.sitesdynamic.comhttp://www.basketsetcetera.com*** Sent via Developersdex http://www.developersdex.com ***
I'm migrating a web based system to SQL server. I'm planning on using the SQL server function NewID() to create unique keys for many of my records in many different tables. I'm just wondering if NewID() is guaranteed to return a value that does not already exist in my database. I mean obviously once you have a certain number of records (a hell of a lot) you'd be breaking the odds to never come up with a duplicate. Do I need to make sure the result of NEWID() doesn't already exist?Thanks
Function GUID() As String GUID = System.GUID.NewGuid().ToString() End Function
GUID is always 36 characters, for example:
1737be72-fe96-4c3c-b455-3730b049bef9
What the best way to store this in a MS SQL database? I'm thinking of using a fixed length string (char). Is there a better way than to just store this 36 character field?
I've googled everything about GUID, seems there is no good thing to say about it. Here's my scenario, a purchase order (PO) application:
We want to have a centralized database with remote sites connected to it
Some of the sites are without connection, they will have their own servers with scheduled replication to the centralized database. The design is something like this:
Each PO will have many revisions
Each revision will have many PO line items
Each PO line item will have many Delivery Schedules In the past i used int IDENTITY as transaction ID in revision and line item tables.
transaction ID in revision table is FK to line item table, and transaction ID line item table is FK to Delivery Schedules table.
This work well in standalone database.
Now that we need to merge replicates, int IDENTITY produced in remote DB will conflict with IDENTITY produced in central DB.
I'm thinking of using GUID to replace int IDENTITY.
Question:
How bad is my decision?
Can't GUID size indexing problem be solved with partitioning?
Can you suggest other alternatives to GUID, based on the above scenario? Thanks in advance
Here's a problem description I read on another post but I have the same issue:
I am trying to Import Data from a csv file into a SQL Sever table. The Data being imported has a Unique Identifier in it but it is being considered as DT_WSTR datatype in SSIS
When i directly try to import, it gives an error:
The conversion returned status value 2 and status text "The value could not be converted because of a potential loss of data.".
I Tried to use Data Conversion to convert it to DT_GUID and import into SQL Server table but it again throws the above error. Anyone has a clue?
How do I update the OrderGUID column in Table B with Values from OrderGUID column in Table A. I have already populated the OrderGUID column in Table A using NEWSEQUENTIALID(). Now I need to populate the OrderGUID column in Table B with Matching GUID values from the OrderGUID Column in Table A.
Does any one have a script to accomplish this task. thanks
Msg 2601, Level 14, State 1, Procedure DFP_report_load, Line 161 Cannot insert duplicate key row in object 'dbo.DFP_Reports_History' with unique index 'ix_report_history_creative_id'.
The duplicate key value is (40736326382, 1, 2015-07-03, 67618862, 355324). Msg 3621, Level 0, State 0, Procedure DFP_report_load, Line 161
The statement has been terminated.
Exception in Task: Cannot insert duplicate key row in object 'dbo.DFP_Reports_History' with unique index 'ix_report_history_creative_id'. The duplicate key value is (40736326382, 1, 2015-07-03, 67618862, 355324).
A UNIQUE INDEX must inherently impose a unique constraint and a UNIQUE CONSTRAINT is most likely implemented via a UNIQUE INDEX. So what is the difference? When you create in Enterprise Manager you must select one or the other.
What's the difference in the effect of the followings: CREATE UNIQUE NONCLUSTERED INDEX and ALTER TABLE dbo.titles ADD CONSTRAINT titleind UNIQUE NONCLUSTERED
I found there're two settings in Indexs/Keys dialog box of the management studio, Is Unique, and Type. The DDL statements above are generated by setting Is Unique to yes plus Type to Index, and just Type to Unique Key, respectively. What's the difference between them?
Hi everyone, I need urgent help to resolve this issue... As far as the performance goes which one is better.. Unique Index(col1, col2) OR Unique constraint(col1, col2) ? Unique constraint automatically adds a unique index and unique index takes care of uniqueness then whats the use of unique constraint ?
BOL says a unique constraint is preferred over a unique index. It also states that a unique constraint creates a unique index. What then is the difference between the two, and why is a constraint preferred over the index?
hi team, .Can i create umique constraint with out unique index.when i am creating a unique constraint sql creates a unique index (default) can i have only unique constraint ?
I am having a problem trying to figure out the best way to get the results I need. I have a table of part numbers that is joined with a table of notes. The table of notes is specific to the part number and user. A row in the notes table is only created if the user has entered notes on that part number. I need to create a search that grabs all matches on a keyword and returns the records. The problem is that it currently returns a row from the parts table with no notes and a separate row with the notes included if they had created an entry. It seems like this should be easy but it eludes me today. Here is the code
Code Snippet create procedure SearchPartKeyword ( @Keyword varchar(250) = null, @Universal_Id varchar(10) = null ) as select p.PartNumber, p.Description, p.ServiceOrderable, n.MyNotes, p.LargestAssembly, p.DMM, p.Legacy, p.Folder, p.Printer from Parts p inner join notes n on p.PartNumber = n.Identifier where n.Universal_ID = @Universal_ID and p.Description like @Keyword union select p.PartNumber, p.Description, p.ServiceOrderable, '' as MyNotes, p.LargestAssembly, p.DMM, p.Legacy, p.Folder, p.Printer from Parts p where p.Description like @Keyword
and the results: PartNo Description SO Notes LA DMM Legacy Folder Printer de90008 MAIN BOARD 1 DGF1 114688 0 0 0 de90008 MAIN BOARD 1 I love this part Really I do DGF1 114688 0 0 0
This could return multiple part numbers and If they have entered notes I want the row with the notes
we are currently using id's as primary key and replication is not part of our project. will this be a problem if we decide to do replication? will microsoft generate an identifier then. what is the advantages of using GUID now or doing it latter?
I'm working on a smart client app that has an offline sql express store and needs to work with several types of central databases (support for multiple products - ms sql, DB2 etc)
While trying to put together some offline functionality that needs the user to create records on the offline sql express data store, we've run into the need of being able to uniquely identify records so replicating the data in the offline store back into the primary database should not be a problem.
The data created offline spans many tables and involves several tables with relation ships - FK etc...Clearly not a simple case of store and forward.
We dont want to get into the mess of performing key replacement during a synch job with the server. Thats way too much trouble.
GUID seems like a good choice, but as always we have several stake holders having different opinions. And with databases other than MS SQL we will have to store them as strings.
To cut to the chase - can we not hash a GUID to get an integer while retaining atleast the same likelyhood of producing unique ids ? [no drop]
I am using a SqlDatasource and need to set a SelectParamter to the ProviderUserKey (The GUID of the user when Profiles are enabled) Can anyone tell me whether it is possible and How? I am currently using the session state to store it in and then using the session=... to get the value into the parameter. Is there a direct way of passing this value into a SelectParameter when using a SqlDataSource? Thanks in advance.
Hi Everyone, I'm trying to create a SQL Delete statement using a string builder and the WHERE clause uses a Guid. Here is the code:stb.Append("DELETE FROM UserRights WHERE UserIDPtr = "); stb.Append(TargetUserID);The resulting string is: "DELETE FROM UserRights WHERE UserIDPtr = e01549fb-edf5-4668-de8b-b13dd5661a6e" When I try to do an ExecuteNonQuery() using the string as the CommandText, I get an error. Invalid column name 'e01549fb',Invalid column name 'edf5',Invalid column name 'de8b',Invalid column name 'b13dd5661a6e' It is also strange that '4668' did not show up as an invalid column name, but I don't think that is relavent to this issue. Can someone show me (or point me to an article) about using Guid's in a text string as a SQL command? Thanks in advance!
My database is using the membership store for all the user information. I added a tabel "Skills" with 3 fields "SkillID (GUID)" "SeekerID (GUID, This is the UserId)" and "SkillName ( Varchar(MAX))" on the page i have a ListView setup to display the SkillName fields based on the SeekerID. The original code was Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load ' Get a reference to the currently logged on user Dim CurrentUser As MembershipUser = Membership.GetUser ' Determine the currently logged on user's UserId value Dim SeekerID As Guid = CType(CurrentUser.ProviderUserKey, Object) End Subthat kept returning string to GUID conversion errors, so i had to change Dim SeekerID As Guid = CType(CurrentUser.ProviderUserKey, Object) to Dim SeekerID As Object = CType(CurrentUser.ProviderUserKey.ToString(), Object) that appears to be working now. On the same page however, I want to insert records into the table, I tried 2 options both of which have a different problem. Option 1: Use a textbox (ID = NewSkill) and a button with the following code on it: Protected Sub SetNewSkill_Click(ByVal sender As Object, ByVal e As System.EventArgs) Dim CurrentUser As MembershipUser = Membership.GetUser Dim SeekerGUID As Object = CType(CurrentUser.ProviderUserKey, Object)
Dim NewSkill As TextBox = CType(FindControl("NewSkill"), TextBox) Dim connectionString As String = ConfigurationManager.ConnectionStrings("QJSdatabase").ConnectionString() Dim insertSql As String = "INSERT INTO Skills(SeekerID, SkillName)VALUES(@SeekerGUID, @NewSkill)" Using myConnection As New SqlConnection(connectionString) myConnection.Open() Dim myCommand As New SqlCommand(insertSql, myConnection) myCommand.Parameters.AddWithValue("@SeekerGUID", SeekerGUID) myCommand.Parameters.AddWithValue("@NewSkill", NewSkill.Text.Trim()) myCommand.ExecuteNonQuery() myConnection.Close() End Using End Sub
Problem: myCommand.Parameters.AddWithValue("@NewSkill", NewSkill.Text.Trim()) gets outlined and returns the error: Object reference not set to an instance of an object
Option 2: Use a DetailsView linked to a SQLDataSource on the page <asp:DetailsView ID="DetailsView1" runat="server" Height="50px" Width="210px" AutoGenerateRows="False" DataSourceID="SqlDataSource2" DefaultMode="Insert"> <Fields> <asp:BoundField DataField="SkillName" HeaderText="Add Skill:" SortExpression="SkillName" /> <asp:CommandField ShowInsertButton="True" /> <asp:TemplateField InsertVisible="False"> <EditItemTemplate> <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox> </EditItemTemplate> <ItemTemplate> <asp:Label ID="Label1" runat="server"></asp:Label> </ItemTemplate> </asp:TemplateField> </Fields> </asp:DetailsView> <asp:SqlDataSource ID="SqlDataSource2" runat="server" ConnectionString="<%$ ConnectionStrings:database %>" DeleteCommand="DELETE FROM [Skills] WHERE [SkillID] = @SkillID" InsertCommand="INSERT INTO [Skills] ([SeekerID], [SkillName]) VALUES (@SeekerGUID, @SkillName)" SelectCommand="SELECT SkillName FROM [Skills]" UpdateCommand="UPDATE [Skills] SET [SkillName] = @SkillName WHERE [SkillID] = @SkillID"> <DeleteParameters> <asp:Parameter Name="SkillID" Type="Object" /> </DeleteParameters> <InsertParameters> <asp:Parameter Name="SeekerGUID" Type="Object" /> <asp:Parameter Name="SkillName" Type="String" /> </InsertParameters> <UpdateParameters> <asp:Parameter Name="SkillName" Type="String" /> <asp:Parameter Name="SkillID" Type="Object" /> </UpdateParameters> </asp:SqlDataSource>
http://junk.icore-studios.com/junk/Codeissues/postresumeerror.html The @SeekerGUID is being generated by the same pageload code as the first chunk i gave (I have 2 variables SeekerID is the GUID converted to string to work with the ListView filter and SeekerGUID is the GUID)
Ultimatly getting either option to work would be fine. Though I think the second would be preferable because I think it'd be easier to replicate later on. Thanks in advance for your time and any help
I am having a hard time updating a database row using a UNIQUEIDENTIFIER. I retrieve the row into a datagrid and then use the GUID as a parameter to a stored procedure, but it doesn't update. If I run the query in SQL Analyser ... it works. Any ideas ? Here's my stored proc ... I tried passing a varchar and doing the conversion in the SP ... no go !! I am using MApplicationBlockD.
CREATE PROCEDURE spScanUpdate @id varchar (100), @name varchar (75) AS DECLARE @GUID_ID as uniqueidentifier SELECT@GUID_ID = CAST ( @id as uniqueidentifier )
UPDATE tScan SET name = @name WHEREid = @GUID_ID GO
I use MS SQL Server 2005...Is there a structural advantage/disadvantage with using GUID as oposed to an integer?(also I use the sqltableprofileprovider and it doesnt seem to work with uniqueidentifiers)
I have a database with tables with GUID's als primary keys.
Because of the uniqueness GUID's are a performance hit on INSERT records.
So I wanted to use NEWSQUENTIALID() to make INSERTS faster.
Does NEWSQUENTIALID() increase performance as well with SELECT statements? Or is the benefit between NEWID() and NEWSQUENTIALID() only when INSERTing records?
I'm reluctant to admit I'm in love with uniqueidentifiers AKA guid's.
However, this love comes with a cost because of the size and thus SQL Cache and thus IO reads (and fragmented index pages and so on)
My love has to do with generic programming and keeping multiple database updateable (adding core functionality with the flexibility to let users add and change data in tables that have core data in it as well). Also merging databases is easy or relate different entities by storing a metadata link table.
So, what I'm trying to do is making the disadvantages as small as possible.
So I'm using NEWSEQUENTIAL Id's and retrieve new made records with OUTPUT as TABLE.
So I changed the default CLUSTERED INDEX as NON-CLUSTERED.
I'm not fond on usings numerics for some primary keys and uniqueidentifiers for others.
What else can I do to keep using GUID's as primary keys with as less disadvantages as possible?
Hi,Is there any replace for "Select @@identity" that could return "justinserted" GUID as a primary key?Has anyone tested what's faster, working with Guid or Autonumber ?
I have been trying to setup the GUID new GUID when I add a row into a Pocket PC WM 5.0 Mobile SQL (*.sdf) utilizing C# through Visual Studio 2005 - targetting Pocket PC Smart Device
I am reading a book and it talks a little bit about using GUIDs as primary keys. I am very confused about this because if this is a generated value per table, how could you use it as a foreign key in another table as it appears to be uniquely generated per table. Here is the code in the book which I don't understand. Can someone explain this in simple terms?
I know the identity column would be a problem if I had a multi-terabyte database with huge tables, so what do I do in this situation?
